This class contains an event loop based on Linux's epoll interface. More...

#include <Loop.h>

Classes
class	Lock
	Lock objects are used to synchronize between the Event::Loop thread and other threads. More...
struct	NoOpLockable
	Lockable type that compiles out entirely. More...
class	NullTimer
	Used in breakTimer, whose purpose is not to handle events but to break runForever() out of epoll_wait. More...
Public Member Functions
	Loop ()
	Constructor.
	~Loop ()
	Destructor.
void	runForever ()
	Run the main event loop until exit() is called.
void	exit ()
	Exit the main event loop, if one is running.
Private Member Functions
	Loop (const Loop &)
Loop &	operator= (const Loop &)
Private Attributes
int	epollfd
	The file descriptor used in epoll calls to monitor other files.
NullTimer	breakTimer
	Used by Event::Loop::Lock to break runForever() out of epoll_wait.
bool	shouldExit
	This is a flag to runForever() to exit, set by exit().
std::mutex	mutex
	This mutex protects all of the members of this class defined below this point, except breakTimerMonitor.
uint64_t	runningThread
	The thread ID of the thread running the event loop, or Core::ThreadId::NONE if no thread is currently running the event loop.
uint32_t	numLocks
	The number of Lock instances, including those that are blocked and those that are active.
uint32_t	numActiveLocks
	The number of Locks that are active.
uint64_t	lockOwner
	The thread ID of the thread with active Locks, or Core::ThreadId::NONE if no thread currently has a Lock.
Core::ConditionVariable	safeToLock
	Signaled when it may be safe for a Lock constructor to complete.
Core::ConditionVariable	unlocked
	Signaled when there are no longer any Locks active.
struct LogCabin::Event::Loop::NoOpLockable	extraMutexToSatisfyRaceDetector
Event::Timer::Monitor	breakTimerMonitor
	Watches breakTimer for events.
Friends
class	Event::File

Detailed Description

This class contains an event loop based on Linux's epoll interface.

It keeps track of interesting events such as timers and socket activity, and arranges for callbacks to be invoked when the events happen.

Definition at line 38 of file Loop.h.

Constructor & Destructor Documentation

LogCabin::Event::Loop::Loop ( )

Constructor.

Definition at line 97 of file Loop.cc.

LogCabin::Event::Loop::~Loop ( )

Destructor.

The caller must ensure that no events still exist and that the event loop is not running.

Definition at line 113 of file Loop.cc.

LogCabin::Event::Loop::Loop ( const Loop & ) [private]

Member Function Documentation

void LogCabin::Event::Loop::runForever ( )

Run the main event loop until exit() is called.

It is safe to call this again after it returns. The caller must ensure that only one thread is executing runForever() at a time.

Definition at line 124 of file Loop.cc.

void LogCabin::Event::Loop::exit ( )

Exit the main event loop, if one is running.

It may return before runForever() has returned but guarantees runForever() will return soon.

If the event loop is not running, then the next time it runs, it will exit right away (these semantics can be useful to avoid races).

This may be called from an event handler or from any thread.

Definition at line 168 of file Loop.cc.

Loop& LogCabin::Event::Loop::operator= ( const Loop & ) [private]

Friends And Related Function Documentation

friend class Event::File [friend]

Definition at line 194 of file Loop.h.

Member Data Documentation

int LogCabin::Event::Loop::epollfd [private]

The file descriptor used in epoll calls to monitor other files.

Definition at line 109 of file Loop.h.

NullTimer LogCabin::Event::Loop::breakTimer [private]

Used by Event::Loop::Lock to break runForever() out of epoll_wait.

Definition at line 114 of file Loop.h.

bool LogCabin::Event::Loop::shouldExit [private]

This is a flag to runForever() to exit, set by exit().

Protected by Event::Loop::Lock (or mutex directly inside runForever()).

Definition at line 120 of file Loop.h.

std::mutex LogCabin::Event::Loop::mutex [private]

This mutex protects all of the members of this class defined below this point, except breakTimerMonitor.

Definition at line 126 of file Loop.h.

uint64_t LogCabin::Event::Loop::runningThread [private]

The thread ID of the thread running the event loop, or Core::ThreadId::NONE if no thread is currently running the event loop.

This serves two purposes: First, it allows Lock to tell whether it's running under the event loop. Second, it allows Lock to tell if the event loop is running.

Definition at line 135 of file Loop.h.

uint32_t LogCabin::Event::Loop::numLocks [private]

The number of Lock instances, including those that are blocked and those that are active.

runForever() waits for this to drop to 0 before running again.

Definition at line 142 of file Loop.h.

uint32_t LogCabin::Event::Loop::numActiveLocks [private]

The number of Locks that are active.

This is used to support reentrant Lock objects, specifically to know when to set lockOwner back to Core::ThreadId::NONE.

Definition at line 149 of file Loop.h.

uint64_t LogCabin::Event::Loop::lockOwner [private]

The thread ID of the thread with active Locks, or Core::ThreadId::NONE if no thread currently has a Lock.

This allows for mutually exclusive yet reentrant Lock objects.